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Work in progress: CCITT Encoder

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Schmidor
2015-10-08 00:38:31 +02:00
parent 8e11d95fd6
commit 39b92ab19f
2 changed files with 156 additions and 53 deletions
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imageio/imageio-tiff/src/main/java/com/twelvemonkeys/imageio/plugins/tiff/CCITTFaxEncoderStream.java
+81 -49
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@@ -36,7 +36,7 @@ import com.twelvemonkeys.lang.Validate;
/**
* CCITT Modified Huffman RLE, Group 3 (T4) and Group 4 (T6) fax compression.
*
* @author <a href="mailto:harald.kuhr@gmail.com">Harald Kuhr</a>
* @author <a href="mailto:mail@schmidor.de">Oliver Schmidtmer</a>
* @author last modified by $Author$
* @version $Id$
*/
@@ -96,6 +96,7 @@ public class CCITTFaxEncoderStream extends OutputStream {
if (currentBufferLength == inputBufferLength) {
encodeRow();
currentBufferLength = 0;
}
}
@@ -106,14 +107,18 @@ public class CCITTFaxEncoderStream extends OutputStream {
@Override
public void close() throws IOException {
if (type == TIFFExtension.COMPRESSION_CCITT_T6) {
writeEOL();
writeEOL();
}
fill();
stream.close();
}
// TODO: when to write end EOLs, half filled buffer bytes etc. on end?
private void encodeRow() throws IOException {
int[] tmp = changesReferenceRow;
changesReferenceRow = changesCurrentRow;
changesCurrentRow = tmp;
changesReferenceRowLength = changesCurrentRowLength;
changesCurrentRowLength = 0;
@@ -151,7 +156,15 @@ public class CCITTFaxEncoderStream extends OutputStream {
private void encodeRowType4() throws IOException {
writeEOL();
if (optionG32D) {
// TODO decide whether 1d or 2d row, write k, encode
// do k=1 only on first line. Detect first line by missing reference
// line.
if (changesReferenceRowLength == 0) {
write(1, 1);
encode1D();
} else {
write(0, 1);
encode2D();
}
} else {
encode1D();
}
@@ -168,53 +181,66 @@ public class CCITTFaxEncoderStream extends OutputStream {
int index = 0;
boolean white = true;
while (index < columns) {
int nextChange = columns;
for (int i = 0; i < changesCurrentRowLength; i++) {
if (index < changesCurrentRow[i]) {
nextChange = changesCurrentRow[i];
}
}
int runLength = nextChange - index;
int nonterm = runLength / 64;
Code[] codes = white ? WHITE_NONTERMINATING_CODES : BLACK_NONTERMINATING_CODES;
while (nonterm > 0) {
if (nonterm >= codes.length) {
write(codes[codes.length - 1].code, codes[codes.length - 1].length);
nonterm -= codes.length - 1;
} else {
write(codes[nonterm - 1].code, codes[nonterm - 1].length);
nonterm = 0;
}
}
Code c = white ? WHITE_TERMINATING_CODES[runLength % 64] : BLACK_TERMINATING_CODES[runLength % 64];
write(c.code, c.length);
int[] nextChanges = getNextChanges(index);
int runLength = nextChanges[0] - index;
writeRun(runLength, white);
index += runLength;
white = !white;
}
}
private int[] getNextChanges(int pos) {
int[] result = new int[] { columns, columns };
for (int i = 0; i < changesCurrentRowLength; i++) {
if (pos < changesCurrentRow[i]) {
result[0] = changesCurrentRow[i];
if ((i + 1) < changesCurrentRowLength) {
result[1] = changesCurrentRow[i + 1];
}
break;
}
}
return result;
}
private void writeRun(int runLength, boolean white) throws IOException {
int nonterm = runLength / 64;
Code[] codes = white ? WHITE_NONTERMINATING_CODES : BLACK_NONTERMINATING_CODES;
while (nonterm > 0) {
if (nonterm >= codes.length) {
write(codes[codes.length - 1].code, codes[codes.length - 1].length);
nonterm -= codes.length - 1;
} else {
write(codes[nonterm - 1].code, codes[nonterm - 1].length);
nonterm = 0;
}
}
Code c = white ? WHITE_TERMINATING_CODES[runLength % 64] : BLACK_TERMINATING_CODES[runLength % 64];
write(c.code, c.length);
}
private void encode2D() throws IOException {
boolean white = true;
int lastChange = -1;
for (int i = 0; i < changesCurrentRowLength; i++) { // TODO
// columns-Basiert
// statt references
int nextChange = changesCurrentRow[i];
int index = 0; // a0
while (index < columns) {
int[] nextChanges = getNextChanges(index); // a1, a2
int nextRef = getNextRefChange(lastChange);
int[] nextRefs = getNextRefChanges(index, white); // b1, b2
int difference = nextRef - nextChange;
if (difference < -3) {
// next change nearer than nextRef, PMODE
int difference = nextChanges[0] - nextRefs[0];
if (nextChanges[0] > nextRefs[1]) {
// PMODE
write(1, 4);
lastChange = nextRef;
} else if (difference > 3) {
// next change farer than nextRef, hmode
index = nextRefs[1];
} else if (difference > 3 || difference < -3) {
// HMODE
write(1, 3);
// write runLength(white)
// write runLength(!white)
// i++;
// lastChange = ...
writeRun(nextChanges[0] - index, white);
writeRun(nextChanges[1] - nextChanges[0], !white);
index = nextChanges[1];
} else {
// VMODE
switch (difference) {
@@ -241,24 +267,29 @@ public class CCITTFaxEncoderStream extends OutputStream {
break;
}
white = !white;
index = nextRefs[0] + difference;
}
}
}
private int getNextRefChange(int currentRowChange) {
for (int i = 0; i < changesReferenceRowLength; i++) {
if (changesReferenceRow[i] > currentRowChange) {
return changesReferenceRow[i];
private int[] getNextRefChanges(int a0, boolean white) {
int[] result = new int[] { columns, columns };
for (int i = (white ? 0 : 1); i < changesReferenceRowLength; i += 2) {
if (changesReferenceRow[i] > a0) {
result[0] = changesReferenceRow[i];
if ((i + 1) < changesReferenceRowLength) {
result[1] = changesReferenceRow[i + 1];
}
break;
}
}
return columns;
return result;
}
private void write(int code, int codeLength) throws IOException {
for (int i = 0; i < codeLength; i++) {
boolean codeBit = ((code >> (i)) & 1) == 1;
boolean codeBit = ((code >> (codeLength - i - 1)) & 1) == 1;
if (fillOrder == TIFFBaseline.FILL_LEFT_TO_RIGHT) {
outputBuffer |= (codeBit ? 1 << (7 - ((outputBufferBitLength) % 8)) : 0);
} else {
@@ -271,6 +302,7 @@ public class CCITTFaxEncoderStream extends OutputStream {
clearOutputBuffer();
}
}
System.err.println("");
}
private void writeEOL() throws IOException {